WASHINGTON--Pope Francis beseeched Americans to end hostility toward immigrants in a historic speech before the U.S. Congress on Thursday, weighing in forcefully on a divisive issue that is stirring debate in the 2016 presidential campaign. Bringing a message that America's power and wealth should be used to serve humanity, the 78-year-old pontiff said the United States must not turn its back on "the stranger in our midst." "Building a nation calls us to recognize that we must constantly relate to others, rejecting a mindset of hostility," Francis told the Republican-led Congress in Washington a day after he met with Democratic President Barack Obama. Francis, born in Argentina to an Italian immigrant family, delivered a wide-ranging speech that addressed issues dear to liberals in the United States but also emphasized conservative values and Catholic teachings on the family. The leader of the world's 1.2 billion Roman Catholics called for a worldwide end to the death penalty, which is still used in 31 of the 50 U.S. states, while advocating a more equitable economy to help people "trapped in a cycle of poverty" and a greater effort against climate change driven by human activities. The pope later flew to New York, where he was cheered by throngs lining Fifth Avenue as he headed in his "popemobile" to St. Patrick's Cathedral to the sound of the cathedral bells pealing. With organ music playing and a chorus singing, the pope was welcomed by a crowd of 3,000 inside the cathedral for an evening prayer service. Francis on Friday is due to address the United Nations General Assembly in New York and to celebrate an open-air Mass in Philadelphia on Sunday. His plea on immigration received frequent applause mostly from Democrats but also from Republicans among the lawmakers, Supreme Court justices and other dignitaries packed inside the House of Representatives chamber to hear the first address by a pope to a joint meeting of the U.S. Congress. Harsh rhetoric toward illegal immigrants has featured heavily in the race for the Republican nomination for the November 2016 presidential election. Republican front-runner Donald Trump says if elected he would deport all 11 million illegal immigrants, most of whom are from Latin America like the pope, and the billionaire businessman has accused Mexico of sending rapists and other criminals across the border. Francis, addressing an issue that has cost the Republicans support among increasingly influential Hispanic voters, said America should not be put off by the flow of foreigners from south of the border "in search of a better life." "We must not be taken aback by their numbers, but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation. To respond in a way which is always humane, just and fraternal," he said, speaking softly and in heavily accented English. As he spoke, Francis was flanked by two of America's most influential Catholics: House Speaker John Boehner, a Republican, and Democratic Vice President Joe Biden. Boehner, who often tears up at emotional moments, cried openly during the speech. The United States has grappled for years over what to do with illegal immigrants. Republicans in Congress last year blocked a bipartisan effort to overhaul immigration laws that would have allowed illegal immigrants a chance to win U.S. citizenship. In a Pew Research Center poll conducted in May, 51 percent of 2,002 U.S. adults surveyed said immigrants strengthen the United States because of their hard work and talents, while 41 percent said immigrants are a burden because they take jobs, housing and healthcare. It was is unclear whether the pope's speech will change hearts and minds on immigration. "It doesn't affect my thoughts," said Michael Tipsword, a student at George Washington University and a Catholic. He said Francis' opinion on immigration is more related to humanitarian needs than politics. "I'm a pretty staunch conservative," said Tipsword, standing on the lawn in front of the U.S. Capitol building where thousands watched the speech on a large video screen. Invoking famous American figures Abraham Lincoln and the Reverend Martin Luther King Jr., Francis told U.S. lawmakers who are often caught up in bitter partisan fights that politics should be "an expression of our compelling need to live as one, in order to build as one the greatest common good." Presidential candidates from both sides of the divide held up the pope's comments as evidence that the leader of America's 70 million Catholics agrees with them. Alluding to abortion and euthanasia, the pope cited a "responsibility to protect and defend human life at every stage of its development." But he quickly turned to the abolition of the death penalty, saying "every life is sacred" and "society can only benefit from the rehabilitation of those convicted of crimes." Francis also called for an end to a global arms trade fueled by "money that is drenched in blood, often innocent blood, in the face of the shameful and culpable silence." In remarks welcomed by conservatives, Francis said, "Fundamental relationships are being called into question, as is the very basis of marriage and the family," expressing his opposition to same-sex marriage. To underscore his message of helping the poor, Francis went straight from the U.S. Capitol in his small black Fiat to have lunch with homeless people, telling them there was no justification for homelessness.